JP2000138868A - Imaging device and control method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To pick up the image of a moving object with high image quality over a wide dynamic range by picking up the image of the object twice and outputting signals generated through 1st and 2nd image pickup operations externally. SOLUTION: First and second image pickup operations are conducted on an object and then signals generated by the 1st and 2nd image pickup operations are outputted externally. When a photographer depresses a shutter button 13 of this image pickup device to instruct generation of one picture, a solid-state image pickup element 3 outputs signals of 1st and 2nd images photographed in different exposure times. Memories 7, 8 can respectively store a picture of one frame. The memory 7 stores the 1st image signal and the memory 8 stores the 2nd image signals. An image compositing processor 9 composite the 1st image signal stored in the memory 7 with the 2nd image signal stored in the memory 8 and generates an image signal with a wide dynamic range and to output it externally.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an imaging device,
In particular, the present invention relates to an imaging device for capturing an image having a wide dynamic range and a control method thereof.

[0002]

2. Description of the Related Art A solid-state image pickup device has photodiodes arranged in a two-dimensional matrix and can pick up a two-dimensional image. Each photodiode corresponds to a pixel in the image.

FIG. 11 is a graph showing a photoelectric conversion characteristic of a photodiode in a solid-state imaging device. The horizontal axis indicates the amount of light incident on the photodiode, and the vertical axis indicates the voltage output from the photodiode. Characteristic lines A1, A2,
A3 indicates the characteristics of the first, second, and third photodiodes in the same solid-state imaging device.

The characteristic lines A1 to A3 include a linear region R1 generated when the amount of incident light is small and a saturated region R2 generated when the amount of incident light is large. The linear region R1 is a region where the amount of incident light and the output voltage are proportional. The saturation region R2 is a region where the output voltage is saturated with respect to the amount of incident light.

In the linear region R1, the characteristics A1 to A3 of each photodiode are the same, but in the saturation region R2, the characteristics A1 to A3 of each photodiode are different. In the saturation region R2, the output between the photodiodes becomes non-uniform.
Therefore, white clip processing is performed. The white clip process is a process for forcibly converting a voltage whose output voltage is equal to or higher than the voltage Vw to a voltage Vw.

[0006] An area that can be substantially used for photoelectric conversion for performing white clip processing is a linear area R1. The dynamic range in which photoelectric conversion is possible is determined in principle by the width of the linear region R1.

[0007] Solid-state imaging devices are used in digital still cameras and video cameras. The dynamic range of a solid-state imaging device is very narrow as compared with those of the human eye or photographic film. When the dynamic range is narrow, problems such as loss of white and loss of black occur in the image.

In order to solve this problem, there is a technique of capturing two images having different exposure times and synthesizing the two images. The details will be described with reference to FIGS.

In FIGS. 12A to 12C, similarly to FIG. 11, the horizontal axis indicates the amount of incident light, and the vertical axis indicates the output voltage.

FIG. 12A is a graph showing the photoelectric conversion characteristics of a long-time exposure in the first imaging. Since the exposure is performed for a long time, the output voltage increases even if the amount of incident light per unit time is small. This photoelectric conversion characteristic is also subjected to white clip processing at the voltage Vw.

FIG. 12B is a graph showing the photoelectric conversion characteristics of the short-time exposure in the second imaging. Since short-time exposure is performed, the output voltage with respect to the amount of incident light per unit time becomes smaller than the characteristic of long-time exposure (FIG. 12A). This photoelectric conversion characteristic is also subjected to white clip processing at the voltage Vw.

FIG. 12C shows a photoelectric conversion characteristic obtained by combining the photoelectric conversion characteristic of the first imaging (FIG. 12A) and the photoelectric conversion characteristic of the second imaging (FIG. 12B). It is a graph shown. The combining method is, for example, a method of simply adding both characteristics.

[0013] The dynamic range of the solid-state imaging device can be expanded by using the combined photoelectric conversion characteristics. That is, the photoelectric conversion shows a uniform linear characteristic between the photodiodes even when the amount of incident light is small or large.

In the combined photoelectric conversion characteristics, the inclination in a region where the amount of incident light is large is smaller than the inclination in a region where the amount of incident light is small, but this characteristic is close to human visual characteristics and there is no problem. .

Either the long-time exposure or the short-time exposure may be performed first. Next, the operation of the solid-state imaging device for performing the above processing will be described with reference to FIGS. In these figures, hatched areas indicate areas where electric charges are accumulated.

FIG. 13 is a plan view of an all-pixel read-out type solid-state imaging device, in which signals of all pixels (photodiodes) can be read out to the outside at one time as an image of one frame.

The solid-state image pickup device has a structure for performing photoelectric conversion.
A photodiode 51 in a dimensional matrix, a vertical charge transfer path (VCCD) 52 for transferring charges in the vertical direction,
A horizontal charge transfer path (HC) for transferring charges in the horizontal direction.
CD) 53 and an output amplifier 54 for outputting a voltage corresponding to the charge amount to the outside.

First, as shown in FIG. 13, long-time exposure is started, and charges for the first image are transferred to the photodiode 51.
To accumulate.

Next, as shown in FIG. 14, the charges for the first image stored in each photodiode 51 are read out to the vertical charge transfer path 52 on the right side. By this reading,
The long-time exposure for the first image ends, and the short-time exposure for the second image starts.

Next, as shown in FIG. 15, charges for the first image on the vertical charge transfer path 52 are transferred from top to bottom and supplied to the horizontal charge transfer path 53. Horizontal charge transfer path 5
3 transfers the received charge from right to left and supplies it to the output amplifier 54. The output amplifier 54 outputs a voltage corresponding to the received charge amount. That is, a signal of the first image is output.

At this time, as shown in FIG. 16, charges for the second image are accumulated in the photodiode 51 by the short-time exposure started immediately after the read operation shown in FIG.

Next, as shown in FIG. 17, the charges for the second image stored in each photodiode 51 are read out to the vertical charge transfer path 52 on the right side. By this reading,
The short exposure for the second image ends.

Next, similarly to FIG. 15, the vertical charge transfer path 5
2 to transfer the charge for the second image on top down,
It is supplied to the horizontal charge transfer path 53. Horizontal charge transfer path 53
Transfers the received charge from right to left, and outputs
4 The output amplifier 54 outputs a voltage corresponding to the received charge amount. That is, a signal of the second image is output.

Thereafter, as shown in FIGS. 12A to 12C, the first image and the second image are combined.

[0025]

The above-mentioned operation of the solid-state imaging device has no problem when the subject is stationary.
The following problem occurs when the subject is moving. That is, since the interval between the long exposure for the first imaging and the short exposure for the second imaging is long, the subject for the first imaging and the second imaging for the second imaging are long. The position of the subject is shifted. As a result, the synthesized image
An image in which the subject is blurred.

This can be solved by shortening the exposure time for the second imaging. The exposure for the second imaging starts with the readout processing shown in FIG. 14 and ends with the readout processing shown in FIG. During this time, charge transfer for the first image shown in FIG. 15 is performed. Therefore, the exposure for the second imaging is the first exposure.
It cannot be shorter than the image charge transfer time. 1
The charge transfer time for a frame image is 1/60 to 1 /
It is about 15 seconds.

An object of the present invention is to provide an image pickup apparatus capable of picking up a moving subject with high image quality and a wide dynamic range, or a control method thereof.

[0028]

According to one aspect of the present invention, a plurality of photoelectric conversion elements, each of which generates an electric signal by photoelectric conversion, and a memory for storing a signal generated by the plurality of photoelectric conversion elements. A first imaging is performed by causing a signal storage element, a gate for reading out a signal generated by the photoelectric conversion element to the signal storage element, and causing the plurality of photoelectric conversion elements to generate a signal. A signal is read out to the signal storage element, a second imaging is performed by causing the plurality of photoelectric conversion elements to generate signals under imaging conditions different from the first imaging, and then the first imaging is performed.
Control to output a signal generated by the imaging to the outside from the signal storage element, and then read a signal generated by the second imaging from the plurality of photoelectric conversion elements to the signal storage element and output the signal to the outside An image pickup apparatus is provided, comprising: a unit; and a combining unit that generates an image signal by performing white clip processing and combining the output signals obtained by the first and second imagings.

First and second imaging are performed, and then the first and second imagings are performed.
And the signal generated by the second imaging is output to the outside. The second imaging time is not limited to the time for outputting the signal generated by the first imaging to the outside, but can be short. By shortening the second imaging time, the subject shift between the signals obtained by the first and second imagings can be reduced.

Further, by subjecting the signals obtained by the first and second imagings to white clip processing and combining them, an image signal having a wide dynamic range can be generated.

[0031]

FIG. 1 is a diagram showing a configuration of an image pickup apparatus (for example, a digital camera) according to an embodiment of the present invention.

The lens 1 forms an image of a subject 10 on a solid-state image sensor 3 via a mechanical (mechanical) shutter 2. The opening and closing of the mechanical shutter 2 is controlled by a signal MC from the camera control unit 11. When the mechanical shutter 2 is open, light from the subject 10 reaches the solid-state imaging device 3, and when the mechanical shutter 2 is closed, light from the subject 10 is blocked before reaching the solid-state imaging device 3.

The shutter button 13 is a button operated by a photographer to instruct photographing. Camera control unit 11
Controls the mechanical shutter 2, the CCD driver 4, and the image processing unit 5 based on the timing at which the shutter button 13 is pressed. The power supply 12 is for operating the digital camera.

The CCD driver 4 controls the solid-state imaging device 3. The solid-state imaging device 3 generates an image signal according to the amount of incident light from the subject 10 and outputs the image signal to the image processing unit 5.
The image processing unit 5 has an A / D converter (AD) 6, two frame memories 7, 8, and an image synthesis processor 9.

The solid-state imaging device 3 has a photodiode and a charge transfer path (CCD). The photodiodes correspond to pixels and are arranged two-dimensionally in a vertical direction and a horizontal direction, and convert so-called photoelectric conversion by converting light applied to a light receiving unit into electric charges. The charge transfer path transfers the charge converted by each photodiode and outputs the charge to the A / D converter 6. The A / D converter 6 converts an analog charge amount supplied from the solid-state imaging device 3 into a digital charge amount.

When the photographer instructs the generation of one image by pressing the shutter button 13, the solid-state imaging device 3
It outputs signals of the first image and the second image captured at different exposure times.

Each of the memories 7 and 8 can store one frame of image. The memory 7 stores the first image signal. The memory 8 stores a second image signal.

The image synthesizing processor 9 synthesizes the first image signal stored in the memory 7 and the second image signal stored in the memory 8, generates an image signal having a wide dynamic range, and outputs it to the outside. I do. The method of synthesizing the image signals is, for example, a method of simply adding the two, or a method of multiplying each image signal by a predetermined coefficient and then adding the two.

FIG. 4 is a plan view of the solid-state imaging device 3 described above. Solid-state imaging devices include an all-pixel readout type and an interlaced type. This solid-state imaging device 3 is of an all-pixel readout type, and can read out signals of all pixels (photodiodes) to the outside at once as an image of one frame. On the other hand, in the interlaced type, first, pixels of odd lines are read out as a first field, pixels of even lines are read out as a second field, and the first field and the second field are combined to form an image of one frame. A signal is generated.

The solid-state imaging devices 3 are arranged in a two-dimensional matrix, and include a plurality of photoelectric conversion units (for example, photodiodes) 31 for performing photoelectric conversion and a vertical charge transfer path (for transferring charges in the vertical direction). VCCD) 32 and a horizontal charge transfer path (HCCD) 33 for transferring charges in the horizontal direction.
And an output amplifier 34 for outputting a voltage corresponding to the charge amount to the outside. Both the vertical charge transfer path 32 and the horizontal charge transfer path 33 are charge-coupled devices (CCD).

The vertical charge transfer path 32 is driven by a drive signal φV, and the horizontal charge transfer path 33 is driven by a drive signal φH.

The all-pixel readout type solid-state imaging device 3 has at least one charge transfer stage (charge transfer packet) in the region of the vertical charge transfer path 32 corresponding to each photodiode 31. In order to have one charge transfer stage for each photodiode 31, each photodiode 31
It is necessary to provide three or more electrodes in the region of the vertical charge transfer path 32 corresponding to the above, and to drive in three or more phases.

FIG. 2 is a sectional view of the solid-state imaging device 3 shown in FIG.
It is sectional drawing along the I line. A p-type well 22 is formed on a surface of an n-type silicon substrate (semiconductor substrate) 21. p
The n-type region 23 forming the photodiode 31 and the n forming the vertical charge transfer path 32 are formed on the surface of the mold well 22.
A mold region 24 is formed. n-type region 24 and n on the right
Between the mold region 23, ap ⁺ region 25 constituting a channel stop region is formed.

N-type region 2 constituting vertical charge transfer path 32
A shift gate electrode 27 is formed on 4 via an insulating film (for example, a silicon oxide film) 26. The shift gate signal SG is supplied to the shift gate electrode 27. When the shift gate signal SG having a positive potential equal to or more than a predetermined value is supplied, the charges accumulated in the photodiode 31 are read out to the vertical charge transfer path 32.

The shift gate electrode 27 also functions as a charge transfer electrode. When the drive signal φV is supplied to the charge transfer electrode 27, the vertical charge transfer path 32 transfers the charge.
The drive signal φV is a pulse composed of a ground potential and a predetermined negative potential.

The substrate voltage VOD is supplied to the n-type substrate 21. The p-type well 22 is connected to the ground.

The incident light 28 enters the photodiode 31. Charges accumulate in the n-type region 23 by light irradiation.
If the charges are excessively accumulated in the n-type region 23, the charges overflow from the n-type region 23 to the n-type substrate 21. This structure is called an overflow drain structure.

When the substrate voltage VOD is set to a predetermined value or more, the charges accumulated in the photodiode 31 can be discarded to the n-type substrate 21 and the photodiode 31 can be initialized. This operation is called an electronic shutter. With the electronic shutter, charge accumulation in the photodiode 31 can be started.

FIG. 3 is a timing chart of signals for operating the image pickup apparatus (digital camera) shown in FIG.

The mechanical shutter signal MC is output from the mechanical shutter 2
This signal is for controlling the opening and closing of (FIG. 1). The mechanical shutter 2 opens when the signal is at a high level, and closes when the signal is at a low level.

The substrate voltage VOD has two voltage levels V
1, V2. The voltage level V2 is a voltage for initializing the photodiode 31 by discarding charges accumulated in the photodiode 31 to the substrate. Voltage level V1 is a voltage for operating the overflow drain.

The shift gate signal SG and the charge transfer signal φ
V can read charges from the photodiode 31 to the vertical charge transfer path 32 at a positive potential and transfer charges on the vertical charge transfer path 32 at a negative potential.

The charge transfer signal φH is supplied to the horizontal charge transfer path 33.
This is a signal for transferring the upper charge.

The first exposure time T1 is equal to the shift gate signal SG after the pulse V2 is supplied as the substrate voltage VOD.
Is the time until the pulse V12 is supplied, and is the exposure time for the first imaging. The second exposure time T2 is a time from when the pulse V12 is supplied as the shift gate signal SG to when the mechanical shutter signal MC becomes low level, and is an exposure time for the second imaging.

Hereinafter, the operation of the solid-state imaging device 3 will be described with reference to FIGS. First, as shown in FIG. 4, first exposure (for example, short-time exposure) is started, and charges for the first image are accumulated in the photodiode 31.

This operation corresponds to time t1 in FIG.
By maintaining the mechanical shutter signal MC at a high level, the open state of the mechanical shutter 2 (FIG. 1) is maintained. The mechanical shutter 2 is normally open.

At time t1, the substrate voltage VOD is changed from the voltage V1 (for example, 10 V) to the voltage V2 (for example, 25 to 39).
V) (by an electronic shutter)
The photodiode 31 is initialized. After that, the substrate voltage VOD is returned to the voltage V1. The first exposure time T1 starts when the photodiode 31 is initialized.

Next, as shown in FIG. 5, the charge for the first image stored in each photodiode 31 is read out to the vertical charge transfer path 32 on the right side.

This operation corresponds to the time t2 in FIG. 3, and changes the shift gate signal SG from the voltage V11 (for example, 0 V) to the voltage V12 (for example, 15 V) to reduce the electric charge accumulated in the photodiode 31. The data is read out to the vertical charge transfer path 32. Thereafter, the shift gate signal SG is returned to the voltage V11. By this reading, the first exposure (for example, short-time exposure) T1 for generating the first image ends, and the second exposure (for example, long-time exposure) T2 for generating the second image starts.

Next, as shown in FIG.
(FIG. 1) is closed to end the second exposure. On this occasion,
The charge for the first image is stored in the vertical charge transfer path 32, and the charge for the second image is stored in the photodiode 31.

This operation corresponds to time t3 in FIG. 3, and the mechanical shutter 2 (FIG. 1) is closed by changing the mechanical shutter signal MC from high level to low level. By closing the mechanical shutter 2, the second exposure time T2 ends.

Next, as shown in FIG. 7, the charge for the first image on the vertical charge transfer path 32 is transferred from top to bottom and supplied to the horizontal charge transfer path 33. Horizontal charge transfer path 3
3 transfers the received charge from right to left and supplies it to the output amplifier 34. The output amplifier 34 outputs a voltage corresponding to the received charge amount. That is, a signal of the first image is output.

Since the mechanical shutter 2 is closed during this charge transfer, no new charge is generated in the photodiode 31 and no smear is generated. Smear is a problem that when the photodiode 31 is irradiated with intense light, charges leak from the photodiode 31 to the vertical charge transfer path 32, thereby deteriorating the image quality.

This operation corresponds to time t4 in FIG. 3, and supplies a pulse composed of voltage V11 (for example, 0 V) and voltage V13 (for example, -8 V) as charge transfer signal φV.
As a result, the charges on the vertical charge transfer path 32 are transferred in the vertical direction.

Then, a predetermined pulse is supplied as the charge transfer signal φH. As a result, the charges on the horizontal charge transfer path 33 are transferred in the horizontal direction.

As shown in FIG. 8, all the charge signals of the first image are transferred, and the white clip processing shown in FIG. 11 is performed on the signal of the first image output from the output amplifier 34. The white clipping process is a process of converting an output voltage equal to or higher than the voltage Vw into a voltage Vw. The image signal subjected to the white clip processing is written to the frame memory 7 (FIG. 1).

Next, as shown in FIG. 9, the charges for the second image stored in each photodiode 31 are read out to the right vertical charge transfer path 32.

This operation corresponds to time t5 in FIG. 3, and changes the shift gate signal SG from the voltage V11 (for example, 0 V) to the voltage V12 (for example, 15 V) to reduce the electric charge accumulated in the photodiode 31. The data is read out to the vertical charge transfer path 32. Thereafter, the shift gate signal SG is returned to the voltage V11.

Next, as shown in FIG. 10, the charges for the second image on the vertical charge transfer path 32 are transferred from top to bottom and supplied to the horizontal charge transfer path 33. Horizontal charge transfer path 3
3 transfers the received charge from right to left and supplies it to the output amplifier 34. The output amplifier 34 outputs a voltage corresponding to the received charge amount. That is, a signal of the second image is output.

This operation corresponds to time t6 in FIG. 3, and supplies predetermined pulses as charge transfer signals φV and φH. Thereby, the charges on the vertical charge transfer path 32 and the horizontal charge transfer path 33 are transferred.

Next, the second output from the output amplifier 34
The white clip processing is performed on the image signal. The image signal subjected to white clip processing is stored in a frame memory 8
(FIG. 1).

Next, as shown in FIG. 12C, the first image in the frame memory 7 and the second image in the frame memory 8 are combined. By synthesizing, the dynamic range of the solid-state imaging device can be widened.

As shown in FIG. 3, the second exposure time T2
Starts when the electric charge is read out from the photodiode 31 and ends when the mechanical shutter 2 is closed. During this time, the charges for the first image are accumulated on the vertical charge transfer path 32 and are not output to the outside. The second exposure time T2 does not need to be longer than the charge transfer time for outputting the charges for the first image to the outside. Second exposure time T
2 can be shortened.

Since the second exposure time T2 can be shortened, the interval between the first imaging and the second imaging can be shortened, and the displacement of the subject between both imagings can be reduced. That is, blurring of the subject between the first image and the second image can be reduced, so that the image quality of the combined image can be improved.

The solid-state image pickup device 3 is of the all-pixels readout type, and can read out all the pixels in both the first and second shootings, so that a high-quality image signal can be generated.

Further, the control method of the solid-state imaging device according to the present embodiment can be used by switching from the control method of the solid-state imaging device shown in FIGS.

In the first exposure (T1) and the second exposure (T2), the short exposure and the long exposure may be reversed. First, the advantage of setting the first exposure to short-time exposure and setting the second exposure to long-time exposure will be described.

In FIG. 3, the first exposure time (short-time exposure) T1 is, for example, 1/300 seconds, and the second exposure time (long-time exposure) T2 is, for example, 1/30 seconds. The end of the second exposure time T2 is performed by closing the mechanical shutter 2. The time from when the mechanical shutter 2 starts to close until the mechanical shutter 2 closes is preferably 1/10 or less of the exposure time T2. For example, if the exposure time T2 is 1/30 seconds, the operation time of the mechanical shutter 2 needs to be 1/300 seconds or less.

For example, if the second exposure T2 is performed for a short time (for example, 1
/ 300 seconds), the operating speed of the mechanical shutter 2 needs to be reduced to 1/3000 seconds or less. That is, it is necessary to use the high-speed mechanical shutter 2. Since the high-speed mechanical shutter 2 is expensive, the imaging device (digital camera) itself becomes expensive.

By setting the first exposure to short-time exposure and the second exposure to long-time exposure, an inexpensive low-speed mechanical shutter 2 can be used, so that the cost of the imaging apparatus (digital camera) can be reduced. it can.

Next, the first exposure is performed for a long time, and the second exposure is performed.
The advantage of making the exposure for a short time will be described.

If the first exposure is a short exposure,
After that, the long-time exposure is performed, so that the time required to output the short-time exposed image signal to the outside becomes long. The output of a white pixel defect (white flaw) or dark current in an image becomes larger as the time is longer, the image quality is reduced, and as a result, the yield of the solid-state imaging device is reduced.

On the other hand, if the second exposure is short-time exposure, the time required for outputting the short-time exposed image signal to the outside is shortened. As a result, white pixel defects and the like in the image are reduced, so that the image quality is improved and the yield of the solid-state imaging device is improved.

Next, a modification of the embodiment will be described. In the above embodiment, two imagings (exposures) are performed with different exposure times. However, the present invention is not limited to the exposure time, and two imagings may be performed under different imaging conditions. An example of the imaging condition will be described.

(1) Exposure Time In the above embodiment, the case where the exposure time is made different by the combination of the mechanical shutter and the electronic shutter has been described. However, the exposure time may be made different by another method.

(2) Illuminance of Subject The illuminance in the first imaging and the illuminance in the second imaging are made different using, for example, an illumination device with a variable light source. Further, the illuminance of the subject may be changed by using a flash light emitting device.

(3) Transmittance of Optical System The neutral density (ND) filter is a filter for attenuating light of all wavelengths. By providing this ND filter at the same position as the mechanical shutter 2 shown in FIG. 1, the transmittance of the optical system that enters the photodiode can be made different. Similarly, by providing a liquid crystal device, the transmittance of the optical system can be made different.

(4) Aperture By increasing the diameter of the aperture of the digital camera,
The image to be incident on the solid-state imaging device can be brightened,
By reducing the diameter of the stop, an image incident on the solid-state imaging device can be darkened. Two images can be taken with different apertures.

(5) Number of Exposures By changing the number of exposures, two images can be taken. For example, the number of exposures is changed by changing the number of times the mechanical shutter is opened. In the first imaging, the mechanical shutter is opened only once, and in the second imaging, the mechanical shutter is opened three times. Further, the number of times of exposure may be changed by changing the number of times of light emission of the flash light emitting device.

Instead of a solid-state image pickup device having a charge-coupled device (CCD), the following MOS sensor can be used.

FIG. 18A shows the structure of a MOS sensor. The MOS sensor has two or more cells CL on the same substrate.
They are arranged in a dimensional matrix. Each cell CL is specified by a first address AD1 and a second address AD2, similarly to the RAM.

FIG. 18B shows the structure of each cell CL. The cell CL has a photodiode PD, a read gate MOS transistor TR1, a capacitor C1, and an output MOS transistor TR2, like the DRAM.
The charge stored in the photodiode PD is read out by turning on the transistor TR1, and is stored in the capacitor C1. The charge stored in the capacitor C1 is output to the outside by the transistor TR2. This capacity C1
Corresponds to the vertical charge transfer path 32 in the solid-state imaging device shown in FIG.

The imaging apparatus according to the present embodiment is not limited to a digital camera, but can be applied to an image scanner, a line sensor, a video camera, and the like. This imaging device is particularly suitable for capturing a still image.

The present invention has been described in connection with the preferred embodiments.
The present invention is not limited to these. For example, it will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

[0095]

As described above, according to the present invention,
Since the first and second imagings are performed and the signals generated by the first and second imagings are output to the outside thereafter, the signal generated by the first imaging is output to the outside during the second imaging time. The time for output is not limited, and can be shortened. By shortening the second imaging time, a subject shift between the signals obtained by the first and second imagings can be reduced, and a high-quality image signal can be generated.

Further, by subjecting the signals obtained by the first and second imagings to white clip processing and combining them, an image signal having a wide dynamic range can be generated.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an imaging device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a solid-state imaging device.

FIG. 3 is a timing chart of signals for operating the imaging apparatus.

FIG. 4 is a plan view of the solid-state imaging device showing a first operation according to the embodiment.

FIG. 5 is a plan view of the solid-state imaging device showing a second operation according to the embodiment.

FIG. 6 is a plan view of the solid-state imaging device showing a third operation according to the embodiment.

FIG. 7 is a plan view of the solid-state imaging device showing a fourth operation according to the embodiment.

FIG. 8 is a plan view of the solid-state imaging device showing a fifth operation according to the present embodiment.

FIG. 9 is a plan view of the solid-state imaging device showing a sixth operation according to the present embodiment.

FIG. 10 is a plan view of the solid-state imaging device showing a seventh operation according to the embodiment.

FIG. 11 is a graph showing a photoelectric conversion characteristic of a photodiode in a solid-state imaging device.

FIGS. 12A to 12C are graphs for explaining an image synthesizing process for expanding a dynamic range.

FIG. 13 is a plan view of a solid-state imaging device showing a first operation according to the related art.

FIG. 14 is a plan view of a solid-state imaging device showing a second operation according to the related art.

FIG. 15 is a plan view of a solid-state imaging device showing a third operation according to the related art.

FIG. 16 is a plan view of a solid-state imaging device showing a fourth operation according to the related art.

FIG. 17 is a plan view of a solid-state imaging device showing a fifth operation according to the related art.

FIGS. 18A and 18B are circuit diagrams of a MOS sensor.

[Explanation of symbols]

Reference Signs List 1 lens 2 mechanical shutter 3 solid-state imaging device 4 CCD driver 5 image processing unit 6 A / D converter 7, 8 frame memory 9 image synthesis processor 10 subject 11 camera control unit 12 power supply 13 shutter button 21 n-type silicon substrate 22 p-type well Reference Signs List 23 n-type region 24 n-type region 25 p ⁺ -type region 26 insulating film 27 shift gate electrode (charge transfer electrode) 28 incident light 31, 51 photoelectric conversion unit (photodiode) 32, 52 vertical charge transfer path 33, 53 horizontal charge Transfer path 34, 54 Output amplifier CL cell AD1, AD2 Address PD Photodiode TR1, TR2 MOS transistor C1 Capacitance

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shinji Uya 1-6-6 Matsuzakadaira, Yamato-cho, Kurokawa-gun, Miyagi Prefecture Inside Fujifilm Micro Devices Co., Ltd. (72) Inventor Tetsuo Yamada 1 Matsuzaka-daira, Yamato-cho, Kurokawa-gun, Miyagi Prefecture 6-chome FUJIFILM Micro Devices Co., Ltd. F-term (reference) 4M118 AA02 AB01 BA10 BA14 CA03 DB01 DB03 DB07 DB08 DB11 FA06 FA13 FA26 FA33 FA35 GA10 5C024 AA01 AA03 BA01 CA15 DA04 EA01 FA01 FA11 GA01 GA11 GA26 GA31 GA44 HA04 HA17 HA21 JA24

Claims (12)

[Claims] 1. A plurality of photoelectric conversion elements each generating an electric signal by photoelectric conversion, a signal storage element for storing a signal generated by the plurality of photoelectric conversion elements, and a signal storage element generated by the photoelectric conversion element A gate for reading a signal to the signal storage element; performing a first imaging by causing the plurality of photoelectric conversion elements to generate a signal; reading the generated signal to the signal storage element; A second imaging is performed by causing the plurality of photoelectric conversion elements to generate signals under imaging conditions different from the first imaging, and thereafter, a signal generated by the first imaging is output to the outside from the signal storage element. Control means for reading out the signal generated by the second imaging from the plurality of photoelectric conversion elements to the signal storage element and outputting the readout signal to the outside; And a combining unit that generates an image signal by performing white clip processing and combining the signals obtained by the second imaging and the second imaging. 2. The imaging device according to claim 1, wherein said photoelectric conversion element, signal storage element, and gate are formed on the same semiconductor substrate. 3. The imaging device according to claim 1, wherein said photoelectric conversion element is a photodiode, and said signal storage element is a CCD. 4. The all-pixel read-out type wherein said CCD has at least one signal transfer stage for each photodiode, and can read out signals in all photodiodes to corresponding signal transfer stages. Item 4. The imaging device according to Item 3. 5. The photoelectric conversion element is a photodiode, the signal storage element is a capacitor, and the gate is an MO.
3. The imaging device according to claim 1, wherein the imaging device has a MOS sensor type structure that is an S transistor. 6. The control means according to claim 1, wherein said control means comprises: an exposure time;
2. An imaging condition between the first and second imagings is changed by changing at least one of a transmittance, an aperture, and the number of exposures of an optical system incident on the photoelectric conversion element.
Or the imaging device according to 2. 7. The image pickup apparatus according to claim 1, further comprising a mechanical shutter, wherein the control unit changes an image pickup condition between the first and second image pickups by changing an exposure time by the mechanical shutter. . 8. The imaging device according to claim 1, further comprising an illumination device, wherein the control unit changes an imaging condition between the first and second imaging operations by changing an illuminance of a subject by the illumination device. Imaging device. 9. A liquid crystal device, wherein the control unit changes imaging conditions between the first and second imaging by changing a transmittance of an optical system of a photoelectric conversion element by the liquid crystal device. The imaging device according to claim 1. 10. The control device according to claim 1, wherein the first imaging is performed by long-time exposure, and the second imaging is performed by short-time exposure, so that imaging conditions between the first and second imagings are made different. Item 3. The imaging device according to Item 1 or 2. 11. The control unit according to claim 1, wherein the first imaging is performed by short-time exposure, and the second imaging is performed by long-time exposure, so that imaging conditions between the first and second imaging are changed. Item 3. The imaging device according to Item 1 or 2. 12. A plurality of photoelectric conversion elements each generating an electric signal by photoelectric conversion, a signal storage element for storing a signal generated by the plurality of photoelectric conversion elements, and a signal storage element generated by the photoelectric conversion element. A method for controlling an imaging device having a gate for reading a signal to the signal storage element, comprising: (a) performing a first imaging by causing the plurality of photoelectric conversion elements to generate a signal; A) reading the signals generated by the plurality of photoelectric conversion elements into the signal storage element; and (c) causing the plurality of photoelectric conversion elements to generate signals under imaging conditions different from the first imaging. (D) outputting a signal generated by the first imaging to the outside from the signal storage element; and (e) outputting the signals generated by the second imaging to the plurality of images. of (F) outputting a signal generated by the second imaging from the signal storage element to the outside; and (g) outputting the output first and second signals. 2. A method for controlling an imaging apparatus, which includes, in this order, a step of generating an image signal by performing white clip processing and synthesizing a signal obtained by imaging in 2.